Ribosid

Ribosid is a synthetic nucleoside analog that has been investigated as a therapeutic agent in antiviral medicine. The compound is chemically related to naturally occurring ribose sugars but contains a modified base that interferes with viral replication at the level of nucleic acid synthesis. Because of its structural resemblance to natural ribonucleosides, ribosid is taken up by host cells and phosphorylated into its active monophosphate, diphosphate and triphosphate forms. The triphosphate derivative is incorporated into viral RNA by viral RNA-dependent RNA polymerase, causing chain termination or lethal mutagenesis. In vitro studies have shown activity against hepatitis B virus, hepatitis C virus and several flaviviruses, although the potency is generally lower than that of established nucleoside analogs such as lamivudine or sofosbuvir.

Ribosid was first reported in the early 2010s by a biotechnology company that specialized in novel antiviral agents. Preclinical work demonstrated a favorable safety profile in rodent models, with no significant toxicology observed at doses that achieved therapeutic plasma concentrations. The compound entered phase I clinical trials in 2021, where it was administered orally to healthy volunteers. Pharmacokinetic analyses revealed good oral absorption and a half‑life of approximately 12 hours. The trials also evaluated a single–dose safety cohort and reported only mild gastrointestinal discomfort and transient liver enzyme elevations in a minority of participants.

As of 2024 ribosid has not been approved for commercial use and remains under investigation in ongoing phase II trials for chronic hepatitis B infection. Potential future applications include use as part of combination therapies aimed at completing cure regimens, as well as exploration of its utility in treating emerging RNA virus outbreaks. The compound is also being examined for its possible role in gene editing technologies where controlled nucleoside analogs can modulate reverse transcription processes.